Abstract
Motor stroke has been characterized by disruptions in multiple large-scale functional brain networks. However, it remains unclear whether stroke patients with good hand outcomes show different connectivity profiles within and between networks from those with poor hand outcomes. In this cross-sectional study, we recruited 52 chronic subcortical stroke patients [illness duration (mean±SD): 16±16.2 months] and 52 healthy controls from the local hospital and community from June 2010 to August 2016. We first performed independent component analysis (ICA) on resting-state fMRI data to extract fifteen resting-state networks. Then, we compared the functional connectivity within and between networks across 52 healthy controls, 26 patients with a partially paralyzed hand (PPH), and 26 patients with a completely paralyzed hand (CPH). Compared to the patients with a PPH, the patients with a CPH showed increased connectivity in the contralesional sensorimotor cortex within the contralesional sensorimotor network; the increased connectivity was negatively correlated with the performance of the paretic hand. Moreover, the patients with a CPH, compared to those with a PPH, showed decreased strengths of connectivity between the ipsilesional sensorimotor network and both the dorsal sensorimotor network and ventral visual network; the decreased strengths of connectivity were positively correlated with the performance of the paretic hand. Collectively, our findings suggest that stroke patients with different hand outcomes show distinct functional reorganization patterns in large-scale brain networks. These findings shed light on the network-level neuromechanisms that help explain why stroke survivors in the chronic stage show different hand outcomes.
Highlights
Stroke patients suffering from hand paresis typically have difficulties in daily activities (Veerbeek et al, 2011)
Based on our previous studies among stroke subgroups (Yin et al, 2014; Zhao et al, 2018a) and the two studies that compared independent component analysis (ICA) networks between stroke patients and controls (Wang et al, 2014; Zhao et al, 2018b), we explored whether chronic stroke patients with a completely paralyzed hand (CPH) would show more widespread functional connectivity (FC) reorganization within and between networks than those with a partially paralyzed hand (PPH), which might improve our pathophysiologic understanding of chronic stroke patients with different hand outcomes
We found that mean zFC in the contralesional sensorimotor cortex within the contralesional sensorimotor network (SMN) was negatively correlated with the Fugl-Meyer Assessment of Hand and Wrist (FMA-HW) scores across all stroke patients (r = =−0.44, p = 0.001) (Fig. 3C)
Summary
Stroke patients suffering from hand paresis typically have difficulties in daily activities (Veerbeek et al, 2011). NeuroImage: Clinical 24 (2019) 102065 previous studies have demonstrated that stroke patients suffering from partial hand paresis and complete hand paresis showed different neuroplasticity patterns in topological organization (Yin et al, 2014) and in frequency-dependent local spontaneous oscillations (Zhao et al, 2018a) These studies indicated that it is critical to consider the impact of the hand deficits on functional reorganization in chronic stroke, which may be helpful for understanding the neurophysiologic mechanisms of different hand outcomes after chronic stroke and motivating the development of noninvasive, targeted brain stimulation (Grefkes and Fink, 2012; Grefkes et al, 2010; Koch and Hummel, 2017)
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